Pack Header

MPEG-2 Pack Header

byte 0								byte 1								byte 2								byte 3
7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0
0000 0000 0000 0000 0000 0001 start code																								1011 1010 PACK identifier

byte 4								byte 5								byte 6								byte 7								byte 8								byte 9
7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0
01		SCR 32..30			1	SCR 29..15															1	SCR 14..00															1	SCR_ext									1

byte 10								byte 11								byte 12								byte 13
7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0
Program_Mux_Rate																						1	1	reserved					pack_stuffing_length

PACK identifier -- 0xBA

SCR and SCR_ext together are the System Clock Reference, a counter driven at 27MHz, used as a reference to synchronize streams. The clock is divided by 300 (to match the 90KHz clocks such as PTS/DTS), the quotient is SCR (33 bits), the remainder is SCR_ext (9 bits)
Program_Mux_Rate -- This is a 22 bit integer specifying the rate at which the program stream target decoder receives the Program Stream during the pack in which it is included. The value of program_mux_rate is measured in units of 50 bytes/second. The value 0 is forbidden.
pack_stuffing_length -- A 3 bit integer specifying the number of stuffing bytes which follow this field.
stuffing byte -- This is a fixed 8-bit value equal to '1111 1111' that can be inserted by the encoder, for example to meet the requirements of the channel. It is discarded by the decoder.

The MPEG-1 Pack header is shown for reference only, it is NOT used in DVD-Video.

byte 0								byte 1								byte 2								byte 3
7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0
0000 0000 0000 0000 0000 0001 start code																								1011 1010 PACK identifier

byte 4								byte 5								byte 6								byte 7								byte 8
7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0
0010				SCR 32..30			1	SCR 29..15															1	SCR 14..00															1

byte 9								byte 10								byte 11
7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0
1	Program_Mux_Rate																						1

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